Numerous psychoendocrine studies show that in a stressful or frustrating circumstance, the magnitude of the subsequent stress-repsonse is decreased if the organism is provided with an outlet for frustration. For example, the (glucocorticoid) secretion triggered by electric shock in a rat is diminished if the rat is provided with a bar of wood to gnaw on, a running wheel, or, as one of the most effective outlets, access to another rat to bite.